Scientists have been studying solar influences on the climate for more than 5000 years.Chinese imperial astronomers kept detailed sunspot records, and noticed that more sunspots meant warmer weather. In 1801, celebrated astronomer William Herschel, the first to observe Uranus, noted that when there were fewer spots the price of wheat soared. He surmised that less “light and heat” from the sun resulted in reduced harvests.

Can it really be true that solar radiation, which supplies Earth with the energy that drives our weather and climate – and which, when it varied in the past, is known to have caused major climate shifts – is no longer the principal influence on climate change?

Consider the charts that accompany this article. In locations as widely separated as US, the Arctic and China, they show a strong and direct relationship between temperature and incoming solar radiation -- the data for the US coming directly from Professor Muller’s own BEST data! That such a tight relationship between temperature and solar radiation holds for many disparate geographical areas indicates that the US result cannot be dismissed as just a local aberration.

A strong sun-climate relationship requires mechanisms to exist whereby our sun can both cool and warm the Earth. One such mechanism is fluctuations in the total amount of incoming solar energy, but measurements suggest that this is not a dominant effect. Another cause, and probably a more substantial one, is modulation of the amount of solar radiation that reaches earth’s surface by changes in total cloud cover.

Editor’s Note: The following letter by Dr Colin Summerhayes and the response by Professors Bob Carter and Vincent Courtillot are a continuation of their debate on The Geological Perspective of Global Warming which the GWPF published on 14 February. Dr Summerhayes’ letters have also been published by the Geological Society. We welcome this scientific exchange and hope that readers will find it both enlightening and encouraging.

Dr Colin P. Summerhayes, Scott Polar Research Institute, Cambridge

Dear Dr Peiser,

Thank you for the opportunity to respond to the critique by Drs Carter and Courtillot of my note of 14/2/13 on “The Geological Perspective of Global Warming”. I initially wrote to you to draw attention to Geological Society of London’s statement on this topic, because the geological perspective is usually overlooked in discussions about climate change, and it should not be. But, because Drs Carter and Courtillot moved the debate out of just the geological arena, I am responding in my own capacity, not as a representative of the GSL.

Drs Carter and Courtillot took exception to my use of the phrase “The cooling [of the past 50 million years] was directly associated with a decline in the amount of CO2 in the atmosphere”, saying that correlation was not causation. True. What I should have said was “The cooling of the past 50 million years was driven by a decline in CO2 in the atmosphere.” Prior to the Ice Age of the last 2.6 million years the amount of CO2 in the atmosphere resulted from the interplay between the emission of CO2 by volcanoes and its absorption by the weathering of rocks, especially in mountainous areas, as well as by sequestration in sediments. Methods to determine the likely concentration of CO2 in the atmosphere in the geological past have improved in recent years. They include the numbers of pores (stomata) on leaves, the abundance of the mineral nahcolite (stable above concentrations of 1000 ppm CO2), and the carbon isotopic composition of alkenones from marine plankton. Methods for determining global temperature through time have also improved. We now know that the Eocene was a time of greater volcanic output of CO2, and that the rise of major mountain chains after that time pulled CO2 out of the atmosphere. Geochemical models of the carbon cycle simulate the decline in CO2 after the middle Eocene. Convergence between the CO2 data and the output from those models provide confidence that we understand the process. There is no geologically plausible alternative. We are not talking about a loose association where there is uncertainty about cause as Drs Carter and Courtillot imply. Indeed, even Drs Carter and Courtillot accept that CO2 is a greenhouse gas, and that accumulation of greenhouse gas in the atmosphere warms it. Likewise, its loss will cool the atmosphere.

Dr Colin P. Summerhayes, Vice-President of the Geological Society of London

Dear Dr Peiser,

In the interest of contributing to the evidence-based debate on climate change I thought it would be constructive to draw to your attention the geological evidence regarding climate change, and what it means for the future. This evidence was published in November 2010 by the Geological Society of London in a document entitled “Climate Change: Evidence from the Geological Record”, which can be found on the Society’s web page.

A variety of techniques is now available to document past levels of CO2 in the atmosphere, past global temperatures, past sea levels, and past levels of acidity in the ocean. What the record shows is this. The Earth’s climate has been cooling for the past 50 million years from 6-7°C above today’s global average temperatures to what we see now. That cooling led to the formation of ice caps on Antarctica 34 million years ago and in the northern hemisphere around 2.6 million years ago. The cooling was directly associated with a decline in the amount of CO2 in the atmosphere. In effect we moved from a warm “greenhouse climate” when CO2, temperature and sea level were high, and there were no ice caps, to an “icehouse climate” in which CO2, temperature and sea level are low, and there are ice caps. The driver of that change is the balance between the emission of CO2 into the atmosphere from volcanoes, and the mopping up of CO2 from the atmosphere by the weathering of rocks, especially in mountains. There was more volcanic activity in the past and there are more mountains now.

Hurricane Sandy was not due to global warming, and the Climate Commission is wrong to claim otherwise.

BY CIRCULATING commentary that suggests hurricane Sandy was exacerbated by human-caused global warming, the Climate Commission is wilfully misleading the public. Let us be clear, Sandy was barely a category 1 hurricane as it crossed the densely populated north-east United States.

The enormous damage resulted not from wind, but from flooding and inundation over low-lying areas where housing and commercial development was not designed to cope with such an extreme event. Compounding the issue, vital infrastructure such as levees, public transport systems and power stations were not adequately hardened.

The flooding resulted from heavy rain and a large coastal storm surge at a time of spring tides, all eventualities that could have been predicted.

Many scientists, and now the Climate Commission, have suggested that in a warmer world tropical storms will be more frequent or more dangerous than those previously experienced. This assertion is contentious, and evidence for it is lacking.

Scientific knowledge is always in a state of flux; there is simply no such thing as "settled science", peer reviewed or otherwise.

THE Intergovernmental Panel on Climate Change is a branch of the UN that advises governments on the topic of global warming allegedly caused by human greenhouse emissions.

Contrary to common assumption, the IPCC does not deal with the wider topic of climate change in general. And neither is it the role of the scientists who advise the IPCC to conduct new research as such (though some, incidentally, do).

Rather, the IPCC's task is to summarise the established science as represented in the published scientific literature.

On February 3, 2010, Rajendra Pachauri, head of the IPCC, commenting in The Hindu on the IPCC's 2007 Fourth Assessment Report, said: "Everybody thought that what the IPCC brought out was the gold standard and nothing could go wrong."

Alan Jones is Australia's most popular talk back presenter. Alan Jones is a phenomenon. He is described by many as Australia's greatest orator and motivational speaker. Alan has the mind and capacity to make complex issues understandable to the largest Breakfast audience in Australia.

The head of the Intergovernmental Panel on Climate Change (IPCC) has referred to its work as the gold standard, based on its oft-made claim that it only surveys work published in peer-reviewed professional research papers.

Interestingly, Albert Einstein’s famous 1905 paper on relativity was not peer-reviewed. It is therefore quite clear that peer-review is not a precondition for excellent, indeed epoch-making, scientific research.

So what is a peer-reviewed (also termed refereed) research paper?

Peer-review is a technique of quality control for scientific papers that emerged slowly through the 20th century, only achieving a dominant influence in science after the Second World War. The process works like this. A potential scientific author conducts research, writes a paper on his or her results and submits the paper to a professional journal that represents the specialist field of science in question.

The editor of the journal then scan-reads the paper. Based upon his knowledge of the contents of the paper, and of the activities of other scientists in the same research field, the editor selects (usually) two persons, termed referees, to whom he sends the draft manuscript of the paper for review.

Referees, who are unpaid, differ in the amount of time and effort that they devote to their task of review. At one extreme a referee will criticize and correct the writing of a paper in detail, including making comments on the scientific content; at the other extreme, a referee may merely skim-read a paper, ignoring obvious mistakes in writing style or grammar, and make some general comments to the editor about the scientific accuracy, or otherwise, of the draft paper.

Policymakers have quietly given up trying to cut ­carbon dioxide emissions.

Over the last 18 months, policymakers in Canada, the U.S. and Japan have quietly abandoned the illusory goal of preventing global warming by reducing carbon dioxide emissions. Instead, an alternative view has emerged regarding the most cost-effective way in which to deal with the undoubted hazards of climate change.

This view points toward setting a policy of preparation for, and adaptation to, climatic events and change as they occur, which is distinctly different from the former emphasis given by most Western parliaments to the mitigation of global warming by curbing carbon dioxide emissions.

Ultimately, the rationale for choosing between policies of mitigation or adaptation must lie with an analysis of the underlying scientific evidence about climate change. Yet the vigorous public debate over possibly dangerous human-caused global warming is bedevilled by two things.

First, an inadequacy of the historical temperature measurements that are used to reconstruct the average global temperature statistic.

And, second, fuelled by lobbyists and media interests, an unfortunate tribal emotionalism that has arisen between groups of persons who are depicted as either climate “alarmists” or climate “deniers.”